Here is a typical day with a lab, this was the 12th grade shop assignment for the day. We were to construct a 4520 4 bit counter and test to make sure it works, then and design and build a 8 bit counter using two 4520's. A counter is a digital circuit which is used for a counting pulses and is the widest application of flip-flops. It is a group of flip-flops with a clock signal applied. Counters are of two types, Asynchronous or ripple. Pic are below
Board work and circuit explanation
Datasheet for students
Working example of the 4 bit 4520 shown to students
Our new 3-D printer was out of commission today, it gave a pre-print over current error during the start up process. We only have one service call for this machine a year, due to our service contract. So to save money for the school, I would make an attempt to fix the machine before calling it in and using our one and only service call.
After doing a bit of troubleshooting we found that some of the electronics in the head of the 3D printer machine were shorted out due to the dirt and smoke of being produced near the printers machine location. This machine was moved to the Precision Machine Shop / Metal Fab Welding Shop over last summer. I found a thick haze across a lot of the terminals in the printer head, some pics below:
Error Message By the Objet 360
Thick conductive haze inside machine
I took a sample on a white paper and measured
it with a ohmmeter, it read about 1K ohms per inch
Intake filter after 1 month in new location (PMT)
After school let out, I cleaned up the terminals made sure the machine was level. The machine has been moved several times while inside the PMT shop, and the error has not appeared again. Will update if there is any changes.
Here are some photo of my students using a bench top mini mill machine to build a enclosure for the cat 5 network cable tester project. We used a Jiffy box for this project to speed up the production. We used a table top mini mill to mill out square holes in the box and a file to make small adjustments. The students learn how to use a caliper, dial indicators, swap between millimeter and inches.
During this years open house we were approached by a person in the district that wanted to duplicate a surf board kit. The original kit was laser cut and we would like to make a duplicate, below are some pic of the ribs being traced.
we came up with a way to scan in the image and output it to a solid works file. So far we have traced 10 ribs only 40 to go. The wood we plan to use is 1/8 inch marine grade plywood. This is perfect for our application, there are a couple of ribs that will be oversized that we will have to break down into two sections to fit in the 32" X 20" bed of the laser cutter.
Some of my students found a T-Tech 5000 that was broken and unusable so we decide to fix it. At the same time see how it worked. Some mechanical issues we had to sort out first:
* Top & Bottom Teflon Lead Screw Missing, We found used ones in storage (lucky)
* # 6, #10 Cap screw missing, Mr J. bought some at HD and replaced
* Lead Screw shaft coupler missing, Found this one at Amazon and ordered it
* Broken Limit Switch, We bent back into place, but it need to be replaced
* Spindle motor disconnected, We Reconnected back
* Missing ROM Memory Chips
Both High and Low EPROMS were missing, we found Ver 5.0 on the web. The EPROMs are 27C1001, 1 Meg 128K x 8, Speed is 70nS. To erase the PROMs we used a UV led pointed into the PROM window for 10 minutes, this cleared it for programming.
Here are the HEX files V5.0
HIGH ROM - Is located in IC12 (Marked with H)
LOW ROM - Is located in IC13 (Marked with L)
CMOS SRAMK6T1008C2E 128Kx8 bit Low Power CMOS Static RAM (IC16 and IC17)
Inside the AMC2500 sits a very powerful Freescale MC68332ACFC16. The MC68332, a highly-integrated 32-bit microcontroller, combines high-performance data manipulation
capabilities with powerful peripheral subsystems, Data sheet in link below
Here is a modification to a Milwaukee battery charger, one of the MFW instructors wanted to power 12 volts externally to the charger and battery, basically use the charger and battery as a power source.
So my students took the charger apart and did some research on the battery to make sure that the battery contacts where always on and connected directly to the cell and not switched on or off with a MOSFET. Once verified we tried it out and works get, just like a small UPS power supply.